size vs sound
There are smaller silencers but they produce their quiet by means of a liquid coolant put into the silencer which will shoot out and get louder as the gun is fired usually requiring more coolant be added around 10rnds.
If you want small for a carry type situation the wet silencers work fine are smaller and lighter, if you want to goto the range and plink all afternoon the larger dry silencers are nice not to have to wet them all day long.
The blowback gun like the Makorov pictured will get quieter if an extra power recoil spring is added.
The Beretta you pictured is not blowback it has a lock but not as severe a lockup as some other guns. You can probably get by with a smallish wet silencer without a recoil booster needed with recoil operated guns.
I would ask on silencertalk.com and silencerresearch.com and see if anyone has done this pistol.